Drilling apparatus



Nov. 11, 1952 H, c, JOHANSEN DRILLING APPARATUS 2 SHEETS-SHEET 1 Filed Dec. 12, 1947 I0. W m H H. c. JOHANSEN ,617,630

DRILLING APPARATUS Nov. 11, 1952 Filed Dec. 12, 1947 2 SHEETS-SHEET 2 15222672507; flarrya Jbhavwen.

Patented Nov. 11, 1952 Harry G. J ohansengMichig-ancity; Ind.-, -assignor' to Joy Manufacturing Company, a corporation of Pennsylvania Application December 12, 1947, Serial No. i91,342

-This invention relates to drilling apparatusand more particularly to an automatic chuck and driver especiallydesigned for use with a drill tea or 'kelly' of a rotary type 011 well drilling pharatua l I Ih-an oil welldrilling apparatus of the rotary type; there isusuauy provided, ona commonba'se, drill rod rotating and feedingmechanisms, a 'hoistih mechanism, and a pump for drilling fluid. A drill stem-pr kelly is usually attached ,to' ;;th 'e upper end of the ch11 rod line and may heeither" provided with splineways Oipolygonal er-s section for engagement with a 'splined or a'driver provided with a polygonal openi g drctat'ed bya drive bushing or byarotar'y table; and the drill stem or kelly' issli-dable axially thr ugathe driver and at times may be raised.

13 Claims. (01. 255-22) hydraulically toraise the @111 red line out of the hole' independently of the hoisting cable. In such "drilling apparatus, the drive bushing or rotary table maybe stationary as regards bodily movement or nay be carried by the feeding mechanism bodily to move up and down with the and loweredwith' respect thereto by the usual hoisting cable of the'drilli-ngapparatus; When drilling-in relativelysoft formations, the 'kelly may befedby gravity axially downwardly through the driver or'table under the control of the-hoisting: cable, and the hoisting cable may support the kel'l'y to remove some ofthe weight or the drill-rod linefrom the drill bit. I Whend lung in relatively hard formations, iti sdesil *o" feed-the drillstem'" or kelly, toward the work 'by ahydraulic feeding mechanism to propositive feed and a sensitive control of the movementef the-drill bit at the bottom or the drill hole, and iti's further desirable'automatically to disconnect the" "kelly from the feeding mecuan'ism wnenthe feed retracted to a new feeding position. hlsoL-when' forward feed, is i scaled, itis desirable automaticall'y to con ec the feeding mechanism: to the} kelly. Suchatofli'atic means forconnec-tingthe' feed to' and or releasing the 'reed-rmm thekelly' usually may comprise an automatic "chuck which alltomatidally' grips during forward feediah'd automatically releases when the feed is retracted. Al'smat times it is desirable to operate the jaws of th automatic chuck by manual means wholly .indepehdently' -o'f the movement of-th'e feeding mechanism, s rar exmpl to release the jaws durin'g h'oi sfting or loweringoff the ldrillrqd" line. m-lsuch d nning": ap aratus;- thefdrivef ushing or rotary table =usuai1-yhas keys or apolyg'onal o'pe'n mgxrorvrotaung -splinedfi gr" pol gonal" drive'rod while-permitting free axial-movement of the ve red respect thereto? Further, in sufch I ha apparatusat is desirable; at times; tjd'plf'oonal cli-uclgwhich" rhfayjbe adjusted a winp hydraulic feeding mechanism may be" employed automatic chuck in conventional manners.

An object of the present invention is to pro- 'vide an improved chuck mechanism for connect- I ing the hydraulic feeding mechanism of a rotary drilling apparatus to or releasing th Same from.

the drill stern or lielly. Another object isltio pro-- vide an improved automatic chuck which automatica ly grips thedrill stem or kelly iwne ierc ward feed iseffected and which automatically releases when the" feed is retracted, A further object is' to provide-an improved automatic chuck having anovel arrangement of the chuck jaws and improved means for supporting and operating the jaws; Yet another object" is to provide aid-improved chuck -mechanism'l wherein the rotatable chuck casing carries th driver'jor the drill stem-or kelly and em bodyihg imp'roved adaptor means whereby the driver may b evntirof e pp n means of the automatic chu k};-

and rotatable with the chuck casingffor rotatmg a-drill-stem or kelly; Another objectisfto" pm;

a chuck for grippingadrill stem or kell nect the'hyd-rauligc'feedin'g mechanism t whereby the'fe'e'din'g mechanism ma 'b hydraulically to raise theidrill rod llnelfromj the drill ho'le "independently of the hoisting" cable'jof the drillin'gi'apparatusi These and other objects .and'advantageso'i theinventiori will, however, hereinafter" more fullyappear;

i In the" accompanying drawings there isffshofwn for purposes of illustration one form which the invention ma' ass me in practice; In these dra ings: I 1 v Fig. 1 s ajveitical s'e'ctional'viewpwi pf '5 shown" in full, taken throug -thel feed and rotating'metthanismfs'i'oif arotary oil 11"d 11mg apparatus, with (which an illustrative erhbodi 'mentwoff'the'iniproved chuck mechanism and driver" is associated. f

vide 'animproved chuck mechanism embodying i e releasably attached to the chuck casing; Still nether object is to provide an improved automatic chuclr foiflconhe'cting a hydraulic teed; gn echanism to' "chuck jaws Y Fig. 2 is an enlarged vertical sectional view through the automatic chuck and driver which. are shown in full in Fig. 1, taken on line 2--2 of Fig. 3.

Fig. 3 is a cross-sectional view taken substantially on line 3--3 of Fig. 2.

Fig. 4 is a cross-sectional view taken substantially on l i ne 44 of Fig. 2.

Fig. 5 is a detail sectional view taken substantially on lines 5-5 of Fig. 2.

The rotary oil well drilling apparatus with which the improved chuck mechanism and driver are associated comprises a support I which may be mounted on a base, such as the platform of an automotive vehicle, and this support carries a rotating mechanism generally designated 2 and a feeding mechanism generally designated 3.

The rotating mechanism 2 is herein of a conventional design and includes a power operated rotating member, hereinf preferably in the form of a bevel gear 4, secured to a tubular shaft or drive sleeve 5, the latter suitably journaled in bearings 6 and I supported within a casing 8, herein preferably formed integral with the support I. The casing 8 has usual detachable upper and lower heads 9 and I5 which carry suitable packings, the packing of the upper head seal ingly engaging an inner surface on a member H threadedly secured to the upper end of the drive sleeve 5 and the lower packing sealingly engaging the exterior surface of the lower portion of the drive sleeve. These head packings serve to prevent oil leakage from the casing. The bevel gear 4 may be driven in any suitable manner from any suitable power source, such as by an engine carried by the platform of the automotive vehicle or by thevehicle engine itself. Arranged within and rotatable with the drive sleeve 5, and held therein by an upper plate 12 secured to the member I I, is a drive bushing [3 which has an opening 14 of polygonal cross section which receives a polygonal portion l5 of a rotatable spindle or drive rod I6. If desired, the drive bushing may carry keys which engage splineways on the spindle or drive rod.

The feeding mechanism 3 comprises a pair of parallel vertical feed cylinders l8 suitably rigidly secured to support I at the outer sides of the rotating mechanism 2. Reciprocable in these cylinders are feed pistons 19 having piston rods 20 which extend upwardly through the packed top heads of the feed cylinders. The piston rods 20 are rigidly fixed at 2| at their upper ends to the opposite sides of a cross frame 22 which carries a thrust bearing 23 in which the spindle or drive rod I6 is journaled. The spindle has a shoulder 24 engagingthe bottom of the inner race of the bearing 23, and a sleeve portion 25, threaded on the upper end of the spindle engages at its lower side the top of the inner bearing race Thus, the cross frameand bearing 23 serve as a thrust .head for supporting the spindle l6 which carries the drill rod line. A packing 26, arranged within a recess in the cross frame, has sealing engagement with the exterior surface of the spindle. A cap 21, secured as by screws to the upper side of the cross frame, surrounds the sleeve portion 25 and carries a packing 28sealingly engaging the exterior of the sleeve portion. The packings 26 and 28 serve to prevent oil-leakage from the bearin recess. 'Whenfluid under pressure is supplied to the feed cylinders under the control drive bushing l3, and the spindle is always ro- 4 tated by the drive bushing, whenever the latter is driven, irrespective of the axial position of the spindle with respect thereto.

It will be evident that instead of mounting the drive bushing or rotary table on the stationary support i, it may be carried by the cross frame 22 and suitably driven from its power source through suitable flexible orself-adjusting connections in the manner disclosed in my Patent No. 2,114,305, patented April 19, 1938.

Now referring to the improved chuck mechanism, and more particularly to the improved automatic chuck generally designated 30, it will be noted that the rotatable sleeve portion 25, which is threadedly secured to the spindle or drive rod I5, is herein preferably formed integral with a bottom plate or cover 3| detachably secured, as by screws, to a rotatable chuck casing 32. Also detachably secured, as by screws, to the top of the casing is a plate or cover 33. Detachably connected, as by interlocking lugs 34 and a releasable screw 35, to the top cover 33 of the chuck casing, is a driver casing or adaptor 36 carrying cylindrical keys 3'! seated in concave recesses 38 in the inner wall of the casin and held against axial movement within the casing, as shown. These cylindrical keys slidingly engage splineways 39 in a conventional drill stem or kelly 40 which extends axially through the adaptor and chuck casings into the spindle I6. This kelly is attached in a usual manner at its lower end to the upper end of a conventional drill rod line (not shown) which carries a conventional rotary drill bit. In a drilling apparatus of the type disclosed, the kelly also carries, at its upper end above the adaptor casing 36, a conventional water swivel and lifting bail (not shown) so that drilling fluid may be conducted from the pump of the drilling apparatus through the swivel and kelly and drill rod line to the bottom of the hole to clear away the cuttings from the bit face. The usual hoisting cable of the drilling apparatus is connectible to the lifting bail in a well known manner to eifect raising and lowering of the kelly and drill rod line in the drill hole. The keys 3'! of the adaptor engagin the splineways 39 of the kelly 40 serve to rotate the kelly while the latter is free to slide axially relative to the adaptor and chuck casing. Instead of the keys and splineways, the kelly may be of polygonal cross section and engageable in a polygonal opening in the adaptor-casing in a well known manner.

In this improved construction, arranged in the chuck casing 32 are chuck jaws 42, herein preferably three in number, pivotally connected by transverse pivot pins 43 to toggle links 44 which are, in turn, pivotally connected by parallel pivot pins 45 to sliding blocks 46. These chuck jaws have concave inner surfaces provided with transverse serrations or teeth 41 adapted to grip the cylindrical exterior surface of the kelly. Evidently, if a kelly of polygonal cross section is employed, the jaws would have straight teeth or serrations which would grip the fiat surfaces on the kelly in an obvious manner. The sliding blocks 45have integral guides 48. slidingly received in upwardly and inwardly inclined guideways 49 on the inner walls of the chuck casing, and the block guides are held in the guideways by side gibs 50 secured, as by welding, to the inner casing walls. The chuck jaws are arranged between parallel upper and lower horizontal plates 5! and 52 arranged within the casing chamber and secured to bolts 53, herein preferably three in number, which are threadedly securedat their recesses-58" Qa s sliown in 4-. -The}lowerjspaieing sleeves on thelblolts extend downwardly through openings: 1 59 'infthe lower plate-31% springs 60; acizihghe,-

, may be hydgsmicanr a1 the hydraul-io lowerehdsto; a. shi fterf r in'g flgsurrounding the sleeve: portion- 25- b'eheath the: lower plate 3|.

' Spacih'gasleevesj 5'5:.a,nd 56 respectively betweeh th'eupper-pend lower plates .and jb'etween the lower plate ahdithe shifter ring ser ve -to hold theplates' in proper space'cl -relation; Bairs'of parallelv'erti ca1 plates 51, secured, vas by weldiii between the upper and illbwe'l 'l plates} pfbvide' r adi'ally located which fthechuekfjws' are guided,"

tween--the upper pla'te il arid the plmck jawe 42; yieldingly urge the latterdown and out wardly relative w the 'keliyi The shi-fter jri'nj I ma be provided withany-eui tiible perating ihealnsi' When the 1 shifter rimg is movdk-tdo'w'm Wa'rdl-y; the blocks 46 slide outwardly alohg the' uideways" to efiect release otthe-jaws; through th e tQggl'e link-s 44, from thekl-ly; and when -the jawsifthroi-igh the-toggle nnks, .iiitb opei'htiv re- IQ-tibn with" respect to the kel1y'. nuri'n gautomati operation of'th'e chuck,- upon ihitiatioh -of flown-weird to release 1 the "jaws; but -thej aws wm b'e ca'izsedtb ma,i-nttinirictitinal unmet with the exterior surfa'cejof fthe kel-Iy whi wertll y 'along the keilly, which remanis s ta'itioharyj that time maybe Supp rted: through the dfill' ipd line onthe hole-bottom or by a hoisting cable: When the" feed -is---'f1' 1l-Iyretracted; move:

meht of the feed pistons maybe-reversed again to ldwer the chuck;- thereby-to cause the chuek' jews ah-tomatically-ito grip th'e kelly 'with a powly operaible-"bottomichuok generally designated; I Wifon positively conheeting thekll to: the my;

keny' feedin casing has;Ia 'detachab1e 1ower plate 65 provided .-with a'centna;l openingisthroughi'whichtm kelly extendsz-i Giiide'd ior radielgm'ovemexit in the casingare chuekxja'ws fl operated by screwsgflz Whenthe soreweare-threadedinwardly with re s eet 1110 the: chuck; casing;...the chuck -jaws are moved inwardly; into: [gripping engagement with the :ikelly Thus; I thegkelly may: be: raised hydraulically by the: feeding mechanism" inde pendent]?of the hoistihg smile." The child; jaws 61 arexhowever, releas'edduringnormal drilling openatibzxs. r

; 'm'aa di dtlyi'thrqu rutriwhucm asmgi: B' zthe' ptovision ofi manuat-opemtingmeans"for theaaws 75 "echani'sm Thisehuek comprises a'i-casihg B2-:havingf piperhub- 63 5 tfireadedlyisecurediafi6ltd the1oWe en of the .lspiErldle or'dri ve rod -'l5, as' shown in Fig'a lh This 1 shifter" rihgis moved upwardly, ithe-bloc'k'swjlide" l wardly-alohgth'e "g uidew ysnto movewe chuok "l ks-co nec ingsam-j ws to seidbloohe v I tive1'y-: and inclfihed' with' respect tothe 'plai es 6f of'tjhe automati -chuck; the latter may lie-apex: ated at will independently o'f'movemeht' of the feeding mechahism. The automatic chiiekgieatly increases the overall feeding-speed since when the chuck? reachesits limit of foiward feed, the

,feed" pistons may tie-quickly retracted to anew feeding position without the 'nece's'sit'yaof manualadjustment ofthe chuck jaws, "and the jws aiitomaticallyigrip the kelly w'heh forward" feed isagain resumed." The"manuany'opemlilebottom chiick at the lower end of the drive 'ro'd enableshydraulic raisihg' of the'l-k'lly iri the drillfholein dependently of the hoistirig'cable: The structu isconiparat'ively simplerrizg'gied eindico' pact and may berea'dily applied to a drillingaii'par t e: of a conventional design other advantages of the iinventioii will be c1e21r1y a;pparent' "to these ski-lied'm'theart;

' wnne-az-naveintms a pp'liqejtion speci-iicalljde scribed on'e foi'm which theinve'ntion mayassume' "bodied in various other formsiwithout'hepaitine 111 ,0111 i tskisp'irit 01'" the scope of the appended cl'aim s. V

What-;I*c1aim asm w and desirewo securefby Letters Pateht is: 1 I

i l A-cliuclemeehanism comprising" ;a;rid bodily movable asing throu h wh ieh a kelly isada'pted to (extend; aaf shift ope v v of movement of s aid"rldid1"= jaw s, ,ahd upwardly 2;" A 'chuck mehahisrif'es jset; fort and bodily, movable casing through which a.

and inwardly inclined 'guidewiys on the inner' walliof said easihg-hhd with which' said bIo'dl's chiick'jaws'guided foriddieil movemen .b y said hpp'ozit's and adapted-"to f'grij i a, Rally to cohne'ct the jlatterifor"bodilyfmovelfiexit wiii ter, and said toggle links when said chuck, casing is moved bodily in one direction relative to the kelly swingingtoward parallelism with said planes to increase the gripping action of saidjaws onthe kelly, and an adaptorcasing attached to said chuck casing and carrying means adapted to rotate the kelly with said chuck casing.

4.,A chuck mechanism comprising a rotatable and bodily movable casing through which a kelly is adapted. to extend, a shifter operable exteriorly of said casing, spaced supports arranged within said casing and connectedto said shifter whereby the latter may actuatersaid supports, chuck jaws guided for radial movement between said supports and adapted to grip a kelly to connect the latter for bodily movement with said chuck casing, sliding blocks, toggle links connecting said jaws to said blocks respectively and inclined with respect to the planes of movement of said radial jaws, and upwardly and inwardly inclined guideways on the inner wall of said casing and with which said blocks are slidingly engaged, said blocks when said supports are actuated by said shifter being slidable along said guideways to move said radial;jaws toward the kelly into light frictional contact with the latter, and said toggle linkswhen said chuck casing is moved bodily in one directionrelative to the kelly swinging toward parallelism with said planes to increase the gripping action of said jaws on the kelly, and springs acting between one of said supports and said jaws for urging the latter toward one position, said sliding blocks adapted to hold said jaws in light frictional contact with the kelly as aforesaid whereby upon movement of said chuck casing bodily in said one direction said toggle links effect movement of said jaws into a position to grip the kelly with a powerful toggle ,action.

5. In a drilling apparatus, a chuck having a rotatable and axially movable casing through which a kelly is adapted to extend, gripping jaws guided for radial movement in said casing for connecting the kelly to said casing for axial movement therewith, shiftable guiding means arranged within said-casing for guiding said jaws during such radial movement thereof, operating means at the bottom of said casing for shifting said guiding means axially relative to said cas ing, operating connectionsbetween saidcasing and said jaws and actuated by said shiftable guiding means to efiect movement of said jaws into and out of gripping relationwith the kelly,

and a driver attached to said casing and have ing driving means engaging the kelly; for rotating the latter with saidcasing independently of said jaws. '7 I 6. In a drilling apparatus, the combination comprising a rotatable and axially movable drive rod through which a kelly is adapted to extend, a chuck carried by said drive rod for rotating and axial movements therewith and having a casing secured to said drive rod, said chuck embodying gripping means contained in said casing and operable to engage the kelly to connect the latter to said drive rod for axial movement therewith in one direction, shiftable guiding means contained in said casing and shift: able axially relative thereto, said guiding means providing radial guideways forsaid gripping means, means for shifting said guiding means axially, operating connections between said casing andsaid gripping means and actuated, by said shiftable guiding means, to efiect engagee ment of said gripping means with said kelly, and an adaptor attached to said chuck casing and extending axiallyrwith respect to the chuck, said adaptorhaving means drivingly engaging the kellyat points spaced. from said gripping means axially of said chuck for rotating the kelly with saidchuck casing.

7. In a drilling apparatus, the combination comprising a rotatable and axially movable drive rodthrough which a kelly is adapted to extend, a chuckcarriedby said drive rod for rotating and axial movements therewith and having a casing secured to said drive rod, said chuck embodying gripping means contained in said casing and operable to engage the kelly to connect the latter to said drive rod for axial movement therewith in one direction, a shiftable guiding support contained in said casing and shiftable axially relative thereto, operating connections between said, casing and saidgrippingmeans andactuated by said shiftabl guiding support for efiectingmovement of said gripping means into engagement with-said kelly, said support providing radial .guideways and said gripping means comprising jaws guided in said guideways, means for shifting :said support axially with respect to the chuck, and an adaptor attached to said chuck casing and extending axially, of the latter, said adaptor having means drivingly engaging the kelly at points spaced from said gripping means axially of saidchuck for rotating the kelly with-said chuck casing.

8. In; a drilling apparatus, th combination comprising a support, a drive bushing journaled in said support, an axially movable hollow drive rod connected to said drive bushing for rotation therewith irrespectiveof the axial position of said drive rod with respect thereto, hydraulic feed cylinders carried by said support and containing reciprocable pistons having piston rods projecting through one end of said cylinders, a cross frame to which said piston rods are secured, a thrust bearing carried by said cross frame by which said drive rod is rotatably supported by, said cross frame, a, driver rotatable with'said-drive rod andgdisposed above said cross frame and embodying driving means for engage ing and driving a kellyextending axially through said drive rod, and a chuck carried by said drive ro'd;for, rotating and axialmovements therewith and disposed above'said cross frame and spaced axially of said drive rod with respect to said driver for vconnecting said feed pistons to the kelly; upon axial movement of the drive rod for moving the kelly axially with said chuck, said chuck comprisinga casing secured to said drive rod, said-casing having guideways on its inner walls disposed obliquely with respect to the axial line of th chuck, blocks guided for movement along said guideways, chuck jaws guided for radial movement into and out of engagement with said kelly, toggle links connected between said blocks'and said jaws, and operating connections for shifting said blocks along said guideways to move said radial jaws toward the kelly into light frictional contact with the latter, and said toggle links when said chuck is moved axially in one direction relative to the kelly swinging about their connections with said blocks to igmilreasethe gripping action of said jaws on the 9. In a drilling apparatus, the combination comprising a support, a drive, bushing-journaled in said support, an axially, movable hollow drive rod'connected tosaid drive bushingfor rotation therewith irrespective of the axial position of said drive rod with respect thereto, hydraulic feed cylinders carried by said support and containing reciprocable pistons having piston rods projecting through one end of said cylinders, a cross frame to which said piston rods are secured, a thrust bearing carried by said cross frame by which said drive rod is rotatably supported on said cross frame, an automatic chuck secured to said drive rod for rotating and axial movements therewith and disposed above said cross frame and embodying means for gripping a kelly extending axially through said drive rod upon downward feeding movement of said feed pistons and for releasing the kelly upon retraction of said pistons, said chuck comprising a casing secured to said drive rod, a guiding support shiftable axially within said casing and providing radial guideways, said gripping means comprising jaws guided in said guideways, said jaws having limited yielding movement in said guideways axially of the chuck, means for shifting said support axially, operating connections for said jaws actuated by said shiftable support for effecting yielding engagement of said jaws with said kelly, and a driver carried by said chuck and rotatabl with said chuck, said driver embodying means drivingly engaging the kelly at points spaced axially with respect to said gripping means for rotating the kelly with said chuck and said drive rod.

10. In a drilling apparatus, the combination comprising a rotatable and axially movable drive rod through which a kelly is adapted to extend, rotating means for said drive rod, means for axially moving said drive rod in opposite directions, a chuck carried by said drive rod for rotating and axial movements therewith and including a casing secured to said drive rod and gripping means guided for rectilinear movement radially within said casing and movabl in one direction upon axial movement of said drive rod in one direction for automatically connecting the kelly to said drive rod and movable in the opposite direction upon axial movement of said drive rod in the opposite direction for automatically releasing the kelly from said drive rod, means for effecting such radial, rectilinear movement of said jaws during aforesaid axial movements of said drive rod, said jaw moving means including wedge blocks guided for movement along guideways on said casing inclined slightly upwardly and inwardly with respect to the axial line of the chuck and toggle links connected between said blocks and said jaws, and a driver carried by and rotatable with said chuck casing and extending axially of the latter, said driver embodying means drivingly engaging the kelly at points spaced axially of the latter with respect to said gripping means for rotating the kelly through said rotatable chuck casing.

11. In a chuck mechanism and driver for a kelly of a rotary typ wall drilling apparatus, the combination comprising a rotatable chuck casing through which a kelly is adapted to extend, chuck jaws guided for radial rectilinear movement in said casing and movable in one direction relative to said casing upon bodily axial movement of said chuck casing in one direction into a position to grip the kelly and movable oppositely relative to said casing upon bodily axial movement of said casing in the opposit direction to release the kelly from said chuck casing, means for rotating and bodily axially moving said chuck casing, operating means for effecting such radial, rectilinear movement of said jaws during aforesaid axial movements of said chuck casing, said operating means including wedge blocks, guideways on said casing inclined upwardly and inwardly toward the axial line of the chuck, toggle links connected between said blocks and said jaws and means engaging said blocks for moving the latter along said guideways, yieldable means acting on said jaws for yieldingly urging said jaws toward one position and yieldable to permit movement of said jaws toward kelly gripping position upon movement of said casing in said one direction, and a driver secured to said chuck casing and extending axially of the chuck, said driver having means drivingly engaging the kelly for rotating the kelly with said chuck casing, said driver including an adaptor casing carrying driving means for engaging the kelly at points spaced axially of the chuck with respect to said chuck aws.

12. In a drilling apparatus, a chuck having a rotatable and axially movable casing through which a kelly is adapted to extend, gripping jaws guided for radial movement in said casing for connecting th kelly to said casing for axial movement therewith, shiftable guiding means arranged within said casing for guiding said jaws during such radial movement thereof, operating means at the bottom of said casing for shifting said guiding means axially relative to said casing, and operating connections between said casing and said jaws and actuated by said shiftable guiding means for effecting movement of said jaws into and out of gripping relation with the kelly.

13. A drilling apparatus as set forth in claim 12 wherein said gripping jaws have limited movement relative to said guiding means axially of the chuck, and yieldable means is arranged between said guiding means and said jaws for yieldingly urging the latter toward releasing position.

HARRY C. JOHANSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,690,469 Whinnen Nov. 6, 1928 1,866,934 Johansen July 12, 1932 2,114,305 Johansen Apr. 19, 1938 2,393,603 Beeth Jan. 29, 1946 2,534,213 Alexander Dec. 19, 1950 

